1. Field of the Invention
The invention relates to coordination between a plurality of wireless communication modules, and more particularly to apparatuses and methods for coordination between a plurality of co-located wireless communication modules via only one wire.
2. Description of the Related Art
To an increasing extent, a multitude of communication functions are being merged into mobile devices. As shown in FIG. 1, a cellular phone may connect to a Wireless Local Area Network (WLAN) via a Wireless Fidelity (WiFi) module thereof and simultaneously communicate with a Bluetooth headset (or a Bluetooth car audio, or others) through a Bluetooth module thereof. A WLAN system is typically implemented inside buildings as an extension to Wired Local Area Networks (LANs) and is able to provide the last few meters of connectivity between a wired network and mobile or fixed devices. Referring to FIG. 1, a WLAN is established by an Access Point (AP) connecting to a LAN by an Ethernet cable. The AP typically receives, buffers, and transmits data between the WLAN and the wired network infrastructure. The AP may support, on average, twenty devices and have a coverage varying from 20 meters in an area with obstacles (walls, stairways, elevators etc) to 100 meters in an area with clear line of sight. Bluetooth is an open wireless protocol for exchanging data over short distances from fixed and mobile devices, creating Personal Area Networks (PANs). The cellular phone may receive voice over internet protocol (VoIP) data via the WiFi module and further transmit the VoIP data through an established PAN to the Bluetooth headset, and vice versa. Alternatively, the cellular phone may transmit digital music through the established PAN to be played back in the Bluetooth headset.
Note that the WLAN and Bluetooth systems both occupy a section of the 2.4 GHz Industrial, Scientific, and Medical (ISM) band, which is 83 MHz-wide. As an example shows in FIG. 2, a Bluetooth system uses a Frequency Hopping Spread Spectrum (FHSS) and hops between 79 different 1 MHz-wide channels in a Bluetooth spectrum. A WLAN system carrier remains centered on one channel, which overlaps with a Bluetooth spectrum. When the WiFi module and the Bluetooth module are operating simultaneously in the same area, as shown in FIG. 1, and a Bluetooth transmission occurs on a frequency band that falls within the frequency space occupied by an ongoing WLAN transmission, a certain level of interference may occur, depending on the signal strength thereof. Due to the fact that the WiFi module and Bluetooth module share the same spectrum and also share a single antenna, it is required to prevent the occurrence of interferences therebetween. FIG. 3 is a schematic diagram illustrating interferences between WiFi and Bluetooth modules sharing a single antenna. In FIG. 3, the shared single antenna is switched between WLAN and Bluetooth communication services in a given time slot for transceiving data. If the Bluetooth communication service carries audio data that requires real-time transmission, for example, Synchronous Connection-Oriented (SCO) packets, the Bluetooth communication service would have a higher priority over the WLAN communication service. In this case, when a WLAN transceiving process takes place at the same time as the real-time Bluetooth transceiving process, a time slot will be assigned to the Bluetooth transceiving process and the WLAN transceiving process will be blocked. As shown in FIG. 3, the WLAN receiving operation (Rx operation) 1 occurs in the time slot, while the Bluetooth communication service is idle. Therefore, the Rx operation 1 is performed without interference and an acknowledgement (ACK) message 2 is sent to the WLAN AP (such as the AP in FIG. 1) as a reply message indicating that the Rx operation 1 has been completed. Following the Rx operation 1, another WLAN Rx operation 3 is performed. The Rx operation 3 is also performed without interference because the Bluetooth communication service is in the idle state. However, an ACK message 4 in response to the Rx operation 3 can not be replied to the WLAN AP, as its time slot has already been assigned to the Bluetooth transmitting operation (Tx operation). Accordingly, the Rx operation 3 would be determined to have failed. In response to the failure, the WLAN AP would re-transmit the data frame with a lower data rate in an attempt to successfully transmit data to the WiFi module of the mobile device. Unfavorably, the re-performed Rx operation 3 (denoted as 5), with a prolonged operation period, would be more likely to overlap with the Bluetooth transceiving process. Thus, a data frame would once again be re-transmitted with an even lower data rate than that for the prior re-transmitted data, which would cause even more overlap with the Bluetooth transceiving process than the prior attempt. As a result, because the WLAN and Bluetooth wireless communication services sharing a single antenna are time-division accessed (i.e., only one communication service of WLAN and Bluetooth can be enabled at each time slot), throughput of the WLAN is greatly hindered.
In a general design of such a wireless communication device (e.g., the cellular phone), the WiFi and Bluetooth modules are coupled with a plurality of wires, wherein each of the wires are for communicating specific information concerning the wireless transceiving operations of the WiFi and Bluetooth modules. As shown in FIG. 4, three unidirectional wires are used to carry the information concerning the wireless transceiving operations of the WiFi module to the Bluetooth module, including Tx indicator (i.e., WIFI_TX), Rx indicator (i.e., WIFI_RX), and a transceiving priority indicator (i.e., WIFI_PRIORITY). Referring to FIG. 4, three more unidirectional wires are used to carry the information concerning the wireless transceiving operations of the Bluetooth module to the WiFi module, including a transceiving priority indicator (i.e., BT_PRIORITY), a Tx indicator (i.e., BT_TX), and an Rx indicator (i.e., BT_RX). However, such a signaling interface requires each of the WiFi and Bluetooth modules to have a number of pins corresponding to the number of the wires (e.g., each of the WiFi and Bluetooth modules in FIG. 4 requires six pins for communicating via the wires), and this multi-wire or multi-pin signaling interface results in an additional and unnecessary manufacturing cost and more power consumption.